Discharge lamp



May 28, 1957 D KOLKMAN 2,794,141

DISCHARGE LAMP Filed May 21, 1955- IN VEN TOR DIRK KOLKMAN AGENT DECHARGE LAMP Dirk Kolkman, Eindhoven, Netherlands, assigtaor, by mesne assignments, to North American Phiiips 6on1 pany, Inc, New York, N. L, a corporation of Delaware Application May 21, 1953, Serial No. 356,337 Claims priority, application Netherlands June 23, i952 3 Claims. (Cl. 313--2ill) The invention relates to a discharge lamp comprising a helical discharge tube, a bulb which is pervious to light and surrounds the discharge tube, and a wire-shaped ignition electrode, being externally in contact with the discharge tube.

These discharge lamps are frequently used as sources of flashlight for photographic purposes.

Structural difficulties may frequently arise from the fastening of the ignition electrode to the discharge tube lzmdbthe shock-proof fixing of the discharge tube in the The invention has for its object, among other thing, to solve this problem in a simple, practical manner.

According to the invention the ignition electrode is shaped in the form of a helical wire-tube, the turns of which are in contact with the bulb and with two adjacent turns of the discharge tube.

The outer diameter of the wire-tube is preferably equal to the distance between two adjacent turns of the discharge tube plus about one third of the outer diameter of the discharge tube in order that the ignition electrode should absorb a minimum of light, while a rigid construction is obtained.

The most rigid fixing of the discharge tube is obtained, if the helical wire-tube has about one turn less than the discharge tube.

The helical wire-tube is preferably constituted by a primary helix wound to form a secondary helix.

In order that the invention may be readily carried into effect, it will now be described with reference to the accompanying drawing, which shows one embodiment thereof.

Referring to the figure, reference numeral 1 designates a discharge tube of glass or quartz, filled with xenon or other suitable discharge medium. The discharge tube has an outer diameter of about 6 mms, and is wound in about 4%. turns to form a cylindrical helix having an outer diameter of about 25 mms. and a pitch of about 7 mms.

The discharge tube is surrounded by a substantially cylindrical glass bulb 2, having an inner diameter of about 28 mms. The axis of the discharge tube coincides with the axis of the cylindrical part of the bulb. The upper Patented May 28, 1957 end of the bulb is closed semi-spherically. The bottom end of the bulb is open; to this end is secured a socket 3, having contact pins.

The pins 4 and 5 are connected electrically by means of stay wires 6 and 7 to the main electrodes 8 and 9 of the discharge tube.

The lamp furthermore comprises an ignition electrode 10, which is made of, for example, nickel-chromium wire of about 200 in thickness and which is wound to form a (primary) helix of about 3 mms. in outer diameter, having a pitch of about 3 mms. This wire-tube it) is arranged parallel to the turns of the discharge tube on the periphery thereof in about 3 /2 turns in a manner such that the secondary helical turns of the wire-tube thus formed are in contact each with two adjacent turns of the discharge tube and with the inner wall of the cylindrical part of the bulb. The outer diameter of the secondary helix corresponds, of course, to the inner diameter of the cylindrical part of the bulb 2.

The ends of the ignition electrode 10 are secured to the discharge tube by means of wire rings 11, of which one is connected electrically to an additional pin 12 of the socket 3.

The element 10, consequently, operates not only as an ignition electrode but also as a fastening means for the discharge tube.

What is claimed is:

1. A discharge lamp comprising a light-transparent envelope having a longitudinal axis, a light-transparent sealed gas-filled discharge tube disposed within said envelope, said discharge tube being wound in a helical form whose central axis extends parallel to the longitudinal axis of the envelope, a pair of electrodes disposed within opposite ends of said discharge tube, and an ignition electrode for said discharge tube, said ignition electrode being a helical wire tube embracing the helical discharge tube, said helical wire tube being wound to form a secondary helix aligned with and surrounding the helical discharge tube, the turns of said helical wire tube lying in the space between two adjacent turns of said helical discharge tube and abutting said two turns, the surface of said helical wire tube being in engagement with the inner wall of said envelope.

2. A discharge lamp as claimed in claim 1 wherein the outer diameter of the helical wire tube is about equal to the sum of the distance between two adjacent turns of the discharge tube and about one-third of the outer diameter of the discharge tube.

3. A discharge lamp as claimed in claim 2 wherein the number of turns of the secondary helix is about one less than the number of turns of the discharge tube helix.

References Cited in the file of this patent UNITED STATES PATENTS 

